A network-attached storage is a system that provides data access between servers and storage devices through a computer network. Network-attached shared storage topology may include a processor, a server machine, a storage array, and communication links (such as PCI express). The interfaces in the topology are used as cache storage rather than primary storage. Nonetheless, the performance of the interfaces in a network attached storage topology is limited due to the latency of the system.
For example, the number of IO's that a processor can handle may be limited by the computing power of the processor and then the processor may become a bottleneck that prevents an exploitation of the advantages associated with a higher performance storage device, such as a solid state memory. Second, the cache storage is not hot-pluggable since it is installed inside of a server and therefore reduces the serviceability of the system. Moreover, the system lacks of data storage security and reliability because the topology is non-redundant (e.g. if the storage associated with a server crashed, it is difficult to extract data from the failed array to recover the data that the server has stored). In addition, it is prohibitively expensive if an organization wants to build a network-attached storage system, which requires implementation of cache storage in a server (e.g. it usually costs approximately $30,000 for a 1 TB PCIe card.)